B7054-23-314AV / 54-23-314AV MONITOR MULTI GAS PHD LITE FOR PhD Lite Multi-Gas Detector PhD Lite Gas Detectors are ideal for confined space. Powered by three AA batteries and housed in a completely sealed metal plated case, they monitor up to four atmospheric hazards simultaneously: oxygen, combustible gas, carbon monoxide and hydrogen sulfide. The innovative Duo-Tox dual channel sensor allows PhD Lite Detectors to measure both carbon monoxide and hydrogen sulfide simultaneously without cross interference. Also available in rechargeable with NiMH battery packs. All procedures necessary for day-to-day operation, including fully automatic calibration, are controlled through a single button.